This specification relates to optical communications. Conventional optical communications systems typically include optical amplifiers to provide enough optical power along the fiber links. Typically, optical amplifiers demonstrate amplified spontaneous emission (ASE) noise, which can be described by a noise figure (NF) value that measures a change in signal-to-noise ratio between an input and an output. To maintain a high enough optical signal-to-noise ratio (OSNR) at a receiver end, a high gain and a low noise figure are desired.